[Pw_forum] Doubt on pseudopotential

[Axel Kohlmeyer]

On Wed, 4 May 2005, Eduardo Ariel Menendez P wrote:

dear eduardo,

[...]

EM> Several elements of the 6th row have 4f elBectrons. Hence, I think that
EM> the
EM> valence wavefunctions calculated with plane waves should be orthogonal to
EM> the core 4f orbitals, and an l=3 channel  must be included in the
EM> pseudopotential (otherwise it is the local part). See, for instance, the
EM> Pb pseudopotential

[..]

EM> with the core 4F orbitals. I also checks Tl, Au,Ta, and it is the same.
EM> For this lack of an F channel there is surely a good reason.
EM> Can someone explain me that reason, please?

i have not created those potentials, so i don't know for sure, but
most likely the f-channel was left out, because it had little effect.
the 4f-orbitals are very close to the core, so for elements with
the 4f orbitals filled, there is little effect from them apart from
a 'contraction' of the other orbitals. thus chemically, many elements 
from the 6th row are very similar to their counterparts in the 5th row.
there are a exceptions, though...

a similar situation exists e.g., for the 3d states. please see the
section 'Choosing the valence-core partition' in the pseudo-gen.tex 
document in the atomic_doc directory of the espresso packages.

best regards,
	axel.

EM> 
EM> 
EM> Best regards
EM> Eduardo
EM> 
EM> Eduardo A. Menendez Proupin
EM> Department of Physics
EM> Faculty of Science
EM> University of Chile
EM> Las Palmeras 3425
EM> Ñuñoa, Santiago
EM> Chile
EM> Phone: 56+2+678 74 11
EM> http://fisica.ciencias.uchile.cl/~emenendez/
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EM> 
EM> 

-- 

=======================================================================
Dr. Axel Kohlmeyer   e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.